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br: add unrecoverable system tables list #20145

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br: add unrecoverable system tables list #20145

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b0c84c7
add unrecoverable system tables list
Leavrth Jan 26, 2025
2f2713e
move to another place
Leavrth Mar 3, 2025
13296cb
revise
Oreoxmt Mar 6, 2025
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35 changes: 34 additions & 1 deletion br/br-snapshot-guide.md
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Expand Up @@ -129,6 +129,10 @@ tiup br restore full \

### Restore tables in the `mysql` schema

When the cluster is in snapshot backup, BR backs up system tables as tables with the database name prefix with `__TiDB_BR_Temporary`. For example, the table `mysql.user` will be backed up as `__TiDB_BR_Temporary_mysql.user`.

When the cluster is in snapshot restore, BR at first restores tables with the database name prefix with `__TiDB_BR_Temporary`, in order to avoid conflicts with existing system tables in the cluster. Then when BR starts to restore the system tables, it inserts the data from tables with the database name prefix with `__TiDB_BR_Temporary` to the corresponding system tables through the `REPLACE INTO` SQL.

- Starting from BR v5.1.0, when you back up snapshots, BR automatically backs up the **system tables** in the `mysql` schema, but does not restore these system tables by default.
- Starting from v6.2.0, BR lets you specify `--with-sys-table` to restore **data in some system tables**.
- Starting from v7.6.0, BR enables `--with-sys-table` by default, which means that BR restores **data in some system tables** by default.
Expand All @@ -153,15 +157,24 @@ tiup br restore full \

- Statistics tables (`mysql.stat_*`). But statistics can be restored. See [Back up statistics](/br/br-snapshot-manual.md#back-up-statistics).
- System variable tables (`mysql.tidb` and `mysql.global_variables`)
- [Other system tables](https://github.com/pingcap/tidb/blob/master/br/pkg/restore/snap_client/systable_restore.go#L31)
- [Other system tables](https://github.com/pingcap/tidb/blob/master/br/pkg/restore/snap_client/systable_restore.go#L66)

```
+-----------------------------------------------------+
| advisory_locks |
| analyze_jobs |
| analyze_options |
| capture_plan_baselines_blacklist |
| column_stats_usage |
| dist_framework_meta |
| gc_delete_range |
| gc_delete_range_done |
| global_variables |
| help_topic |
| index_advisor_results |
| plan_replayer_status |
| plan_replayer_task |
| request_unit_by_group |
| stats_buckets |
| stats_extended |
| stats_feedback |
Expand All @@ -172,7 +185,27 @@ tiup br restore full \
| stats_meta_history |
| stats_table_locked |
| stats_top_n |
| table_cache_meta |
| tidb |
| tidb_background_subtask |
| tidb_background_subtask_history |
| tidb_ddl_history |
| tidb_ddl_job |
| tidb_ddl_notifier |
| tidb_ddl_reorg |
| tidb_global_task |
| tidb_global_task_history |
| tidb_import_jobs |
| tidb_mdl_info |
| tidb_mdl_view |
| tidb_pitr_id_map |
| tidb_runaway_queries |
| tidb_runaway_watch |
| tidb_runaway_watch_done |
| tidb_timers |
| tidb_ttl_job_history |
| tidb_ttl_table_status |
| tidb_ttl_task |
+-----------------------------------------------------+
```

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2 changes: 1 addition & 1 deletion faq/backup-and-restore-faq.md
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Expand Up @@ -276,7 +276,7 @@ Note that even if you configures [table filter](/table-filter.md#syntax), **BR d

- Statistics tables (`mysql.stat_*`). But statistics can be restored. See [Back up statistics](/br/br-snapshot-manual.md#back-up-statistics).
- System variable tables (`mysql.tidb`, `mysql.global_variables`)
- [Other system tables](https://github.com/pingcap/tidb/blob/master/br/pkg/restore/snap_client/systable_restore.go#L31)
- [Other system tables](https://github.com/pingcap/tidb/blob/master/br/pkg/restore/snap_client/systable_restore.go#L66)

### How to deal with the error of `cannot find rewrite rule` during restoration?

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